1251805 has 4 divisors (see below), whose sum is σ = 1502172. Its totient is φ = 1001440.

The previous prime is 1251797. The next prime is 1251827. The reversal of 1251805 is 5081521.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 962361 + 289444 = 981^2 + 538^2 .

It is not a de Polignac number, because 1251805 - 2³ = 1251797 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 125176 + ... + 125185.

It is an arithmetic number, because the mean of its divisors is an integer number (375543).

2^1251805 is an apocalyptic number.

It is an amenable number.

1251805 is a deficient number, since it is larger than the sum of its proper divisors (250367).

1251805 is an equidigital number, since it uses as much as digits as its factorization.

1251805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 250366.

The product of its (nonzero) digits is 400, while the sum is 22.

The square root of 1251805 is about 1118.8409180934. The cubic root of 1251805 is about 107.7735596260.

It can be divided in two parts, 125 and 1805, that multiplied together give a square (225625 = 475²).

The spelling of 1251805 in words is "one million, two hundred fifty-one thousand, eight hundred five".